In retelling the story of "Batman Begins" to my son (couldn't let him SEE it fer gawdsake!), he stopped me at the part where young Bruce's parents get killed. "If I were him, I woulda..." and described a valiant fight and triumphant defeat of Joe Chill. "Nope," I stopped him, "In every Batman story this happens to him. The pearls go flying. It wouldn't be Batman otherwise."
Then I realized all your main superheroes are orphans. Clark's parents rocketed him off Krypton before the planet blew up. Poor Peter Parker had to suffer yet another level of torture when his Uncle Ben got kilt. Just like fairy-tale princesses, which are heroes as well; they all have fathers but no mothers. What's that all about? And what does it mean for those of us who are lucky enough to have parents around?
Think of what Bruce's life would have been like if he'd -"wham!"- defeated Joe Chill and saved his parents. He would have had to live up to that bit of heroism his whole life, never developing the chops to go out and actually do anything further with his life, drinking himself to an early playboy grave. Peter Parker would never have been freaked out enough to go nuts on his first bad guy if ONLY Uncle Ben got it and his parents put up a reward. Clark Kent would have simply lived a life of quiet desperation as a mild-mannered Kryptonic reporter. It's like what researchers say about genetic diseases: you don't automatically get them, but have the potential to get them if they're triggered by enough stress. And it's pretty stressful being on your own so early in life. The superhero with the split-personality is the mythic version of all those poor split non-super souls wandering about missing their parents, wishing they could have saved them.
Then again there are all of us split non-super souls wandering about between our parents. Another way to look at the orphan thing is to imagine the potential energy that is set free when your parents are no longer hanging around telling you what you should do with your life. Those of us lucky enough to know our parents into adulthood get to spend so much energy struggling against or processing the parts of ourselves that remind us of them. Or if you prefer to see that glass as half full, you could say that those of us lucky enough to know our parents into adulthood are busy being connected with the family we want to live up to, follow in the footsteps of, and whose values we want to press into the next generation.
It's kind of sad. Superman, Batman, and Spiderman will probably never have kids; they'll either stay stuck fighting bad guys forever, or flare out at the end of their stories someday (wouldn't put it past Stan Lee to take Spidey with him when he goes) with a bright light. At least we know princesses will grow up after the story ends, and their fathers will dandle another generation of princesses (and imagine their dead wives are smiling on them) on their happily-ever-after old knees. And then there's Mr. and Mrs. Incredible to wonder about....